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Process for Improving Yield and Reliability of Thin Insulator Films

IP.com Disclosure Number: IPCOM000062170D
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Nguyen, TN: AUTHOR [+2]

Abstract

As the channel length of MOSFETs is scaled down to submicron range, insulator films of about 100 ˜ or thinner are required for transfer gates and storage capacitors. Such thin films, however, tend to have low yield and reliability problems. The yield reduction is caused by imperfections, such as pin holes and latent defects. The former are responsible for hard-wired shorts, and the latter are responsible for premature breakdown at low currents and fields. The reliability problems result from the low dielectric strength of the thin insulators. This article describes a process for improving the yield and reliability of thin insulator films utilizing a heat pulse system. Thermal oxide was grown on 3.

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Process for Improving Yield and Reliability of Thin Insulator Films

As the channel length of MOSFETs is scaled down to submicron range, insulator films of about 100 ~ or thinner are required for transfer gates and storage capacitors. Such thin films, however, tend to have low yield and reliability problems. The yield reduction is caused by imperfections, such as pin holes and latent defects. The former are responsible for hard-wired shorts, and the latter are responsible for premature breakdown at low currents and fields. The reliability problems result from the low dielectric strength of the thin insulators. This article describes a process for improving the yield and reliability of thin insulator films utilizing a heat pulse system. Thermal oxide was grown on
3.25"<100> 2 ohm-cm P-type silicon wafers to about 100 ~ thick and subsequently annealed in Ar at temperatures from 1000 to 1150OEC for varying times between 5 and 60 seconds in the heat pulse system. Capacitors were fabricated by evaporating aluminum through 60-mil-diameter dot shadow mask, then breakdown tests were performed using the current ramping method [*]. The starting SiO2 film had good yield (88%). Figs. 1-4 show the percentage of hard- wired shorts (S), latent defects (L), very good capacitors that did not break (M) (capable of passing more than 10 mA at approximately 16 MV/cm) and yield (Y= 100-S-L) as a function of annealing temperature and time. The best result was obtained by annealing at 11...